linux/fs/proc
Josh Don a130e8fbc7 fs/proc/uptime.c: Fix idle time reporting in /proc/uptime
/proc/uptime reports idle time by reading the CPUTIME_IDLE field from
the per-cpu kcpustats. However, on NO_HZ systems, idle time is not
continually updated on idle cpus, leading this value to appear
incorrectly small.

/proc/stat performs an accounting update when reading idle time; we
can use the same approach for uptime.

With this patch, /proc/stat and /proc/uptime now agree on idle time.
Additionally, the following shows idle time tick up consistently on an
idle machine:

  (while true; do cat /proc/uptime; sleep 1; done) | awk '{print $2-prev; prev=$2}'

Reported-by: Luigi Rizzo <lrizzo@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lkml.kernel.org/r/20210827165438.3280779-1-joshdon@google.com
2021-10-05 15:51:35 +02:00
..
array.c proc: stop using seq_get_buf in proc_task_name 2021-09-08 11:50:25 -07:00
base.c connector: send event on write to /proc/[pid]/comm 2021-09-08 11:50:25 -07:00
bootconfig.c bootconfig: Change array value to use child node 2021-06-10 13:38:25 -04:00
cmdline.c
consoles.c
cpuinfo.c
devices.c
fd.c procfs/dmabuf: add inode number to /proc/*/fdinfo 2021-07-01 11:06:04 -07:00
fd.h fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
generic.c proc: save LOC in __xlate_proc_name() 2021-05-06 19:24:11 -07:00
inode.c proc: delete redundant subset=pid check 2021-05-06 19:24:11 -07:00
internal.h fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
interrupts.c
Kconfig
kcore.c fs/proc/kcore: use page_offline_(freeze|thaw) 2021-06-30 20:47:28 -07:00
kmsg.c
loadavg.c sched: Make nr_running() return 32-bit value 2021-05-12 21:34:14 +02:00
Makefile
meminfo.c mm: memcontrol: convert NR_FILE_PMDMAPPED account to pages 2021-02-24 13:38:29 -08:00
namespaces.c
nommu.c
page.c
proc_net.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
proc_sysctl.c Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-07-03 11:41:14 -07:00
proc_tty.c
root.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
self.c Revert "proc: don't allow async path resolution of /proc/self components" 2021-02-23 20:32:11 -07:00
softirqs.c
stat.c fs/proc/uptime.c: Fix idle time reporting in /proc/uptime 2021-10-05 15:51:35 +02:00
task_mmu.c mm: remove VM_DENYWRITE 2021-09-03 18:42:01 +02:00
task_nommu.c
thread_self.c Revert "proc: don't allow async path resolution of /proc/thread-self components" 2021-02-23 20:32:11 -07:00
uptime.c fs/proc/uptime.c: Fix idle time reporting in /proc/uptime 2021-10-05 15:51:35 +02:00
util.c
version.c
vmcore.c vmalloc: remove redundant NULL check 2021-02-24 13:38:30 -08:00